Catalyst system and process for preparing polymers from cationically polymerizable monomers

ABSTRACT

A CATALYST IS PREPARED BY REACTING ALKYL ALUMINUM DIHALIDE IN THE ABSENCE OF A HYDROCARBON SOLVENT, WITH A COBALT SALT TO FORM A BLUE LIQUID COMPLEX. THE CATALYST SO FORMED MAY BE USED TO PREPARE HIGHLY UNSATURATED POLYMERS AND COPOLYMERS OF CATIONICALLY POLYMERIZABLE MONOMERS. THE POLYMERS OF THIS INVENTION ARE RUBBERY HIGH MOLECULAR WEIGHT MATERIALS. THE PREFERRED MONOMERS ARE ISOBUTYLENE AND ISOPRENE. THE PREFERRED ALKYL ALUNIMUM HALIDE IS ALUMINUM ETHYL DIHALIDE AND THE PREFERRED COBALT SALTS ARE COCL2 COBALT BROMIDE AND COBALT ACETONYL ACETONATE.

United States Patent CATALYST SYSTEM AND PROCESS FOR PREPAR- INGPOLYMERS FROM CATIONICALLY PO- LYMERIZABLE MONOMERS Joseph P. Kennedy,Cranford, N.J., assignor to Esso Research and Engineering Company, acorporation of Delaware No Drawing. Filed Apr. 14, 1969, Ser. No.816,058

Int. Cl. C08d 1/14, 3/04, 3/06 US. Cl. 260-853 19 Claims ABSTRACT OF THEDISCLOSURE A catalyst is prepared by reacting alkyl aluminum dihalide,in the absence of a hydrocarbon solvent, with a cobalt salt to form ablue liquid complex. The catalyst so formed may be used to preparehighly unsaturated polymers and copolymers of cationically polymerizablemonomers.

The polymers of this invention are rubbery high molecular weightmaterials. The preferred monomers are isobutylene and isoprene. Thepreferred alkyl aluminum halide is aluminum ethyl dihalide and thepreferred cobalt salts are CoCl cobalt bromide and cobalt acetonylacetonate.

BACKGROUND OF INVENTION This invention relates to a catalyst forpreparing high molecular weight polymers and copolymers of cationicallypolymerizable monomers. The copolymers prepared by this process havehigher unsaturation than conventional butyl rubber copolymers.

It is well known to the art that anionic coordinated catalyst systemsmay be prepared by reacting aluminum ethyl dichloride (AlEtC1 withcobalt chloride in a hydrocarbon solvent. This catalyst system is usefulin the preparation of cis-l,4-polybutadiene. (See for example US. Pat.3,135,725 and British Pat. 827,365, incorporated herein by reference.)

These patents disclose preparation of cis-1,4-polybutadiene usingcatalysts prepared by dispersing anhydrous cobalt chloride in ahydrocarbon solvent such as toluene or xylene, reacting it with trialkylaluminum, separating the dark inactive precipitate so formed and usingthe clear liquid obtained as an active catalyst containing about twomoles of chlorine for every mole of aluminum.

Modifications of this polymer system wherein a soluble organosiliconcompound containing silicon-oxygen bonds have been prepared (see US.Pat. 2,977,349). In all the aforementioned disclosures the product issubstantially cis-l,4-polybutadiene and the polymers are prepared in thehydrocarbon solvent. It has been found that using these systems, it isnot possible to form copolymers of isoolefins with conjugatedmultiolefins in the hydrocarbon solvents.

SUMMARY OF INVENTION It has surprisingly been found that a catalystcomplex of an aluminum alkyl dihalide and cobalt chloride may beprepared in the absence of solvent to give a blue liquid catalystcomplex which is suitable for preparing trans- 1,4-polybutadiene andcopolymers of isoolefins with con jugated multiolefins.

It is preferred in the preparation of the catalyst that no solvent beused. Polymerization of the monomers is carried out in a polar organicsolvent. The catalyst complex may be dissolved in such a polar solventprior to use.

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DETAILED DESCRIPTION OF THE INVENTION This invention relates to acatalyst complex prepared by reacting an alkyl aluminum dihalide with acobalt salt,

wherein X is halogen, and R is C to C alkyl, phenyl, C to C alkylaryl orC to C aralkyl.

Illustrative of the alkyl aluminum dihalides which may be used arealuminum ethyl dichloride, aluminum ethyl dibromide, aluminum butyldichloride, aluminum phenyl dibromide, aluminum phenyl dichloride, andaluminum phenyl diiodide.

Of the salts suitable for use in the preparation of the cobalt complexesof this invention, cobalt chloride is preferred. Various other cobaltsalts may be used. For example, such cobalt salts as cobalt bromide,cobaltacetonyl acetonate, cobalt acetate, etc., may be used.

In the preparation of the catalyst complex of this invention about .01to about 1 mole of anhydrous cobalt chloride is reacted in the absenceof hydrocarbon solvent with about 1 to about 10 moles of aluminum alkyldihalide at a temperature of about 50 to 100 0.; preferably about 60-90C.; more preferably about -85 0.; most preferably about to about C. fora period of about 30 minutes to about 24 hours, preferably about 45minutes to about 18 hours, more preferably about 1 to about 3 hours. Adark blue solution is obtained. The system is cooled at room temperatureand the excess undissolved cobalt chloride is filtered off. The complexso formed will have a cobalt to aluminum mole ratio of about 0.01 toabout 0.5; more preferably about 0.03 to about 0.25; most preferably0.05 to about 0.1; e.g. 0.08.

In the preparation of the polymers of this invention, any cationicallypolymerizable multiolefin may be homopolymerized or copolymerized with acationically polymerizable isoolefin. Illustrative of the multiolefinswhich may be used in the practice of this invention are isoprene,butadiene, 2,3-dimethyl butadiene, chloroprene, piperylene,2,S-dimethylhexadi-2,4-ene, cyclopentadiene, cyclohexadiene, andmethylcyclopentadiene. Illustrative of the isoolefins which may be usedin the practice of this intion are isobutylene, Z-methyl-I-butene,S-methyl-l-butene, 4-methyl-1-pentene and ,B-pinene.

Polymerization may be carried out at a temperature of about -20 to about120; more preferably about --70 to about 110; most preferably about toabout --ll0 C.

It is essential in the practice of this invention that thepolymerization of the polymers and copolymers be carried out in a polarorganic solvent. The term polar organic solvent as used in thespecification and claims means organic solvents having a dielectricconstant of about 3 to about 50; preferably about 6 to about 20; morepreferably about 8 to about 15; most preferably about 9 to about 12.Illustrative of these polar organic solvents are methyl chloride, ethylchloride, propyl chloride, chlorobenzene, ortho chlorotoluene, etc.Generally any halo- 3 genated organic compound which is normally liquidunder polymerization conditions may be used.

Although the process may be carried out with blends with theaforementioned polar solvents in conjunction with nonpolar hydrocarbonsolvents, it is preferred that the 4 overnight and a dark precipitatewas obtained. 35 ml. of toluene and ml. of isobutylene were added tothis mixture with stirring at ambient temperature and refluxing toprevent the escape of isobutylene. After six hours of stirring, a 3 ml.aliquot was withdrawn and methanol added.

process be carried out in the absence of nonpolar hydro- 5 No polymerwas formed. Similar sampling after 16 hours carbon solvents. Where suchnonpolar hydrocarbon 501- also resulted in no polymer formation.

vents are used in conjunction with the polar organic sol- The experimentwas repeated using triethyl aluminum vents of this invention, thesolvent blend should contain instead of tributyl aluminum. Again, nopolyisobutylene no more than 50 volume percent of nonpolar hydrocarwasobtained. Similarly, when aluminum diethyl chloride bon solvent;preferably about 10 to about 25 volume perwas used in place of tributylaluminum, no polymer was cent; most preferably about 0 to about 20volume perobtained. This example serves to illustrate that the catalystcent. Illustrative of the hydrocarbon solvents which may complexprepared in the manner of US. Pat. 3,135,725 be used in the practice ofthis invention in conjunction does not homopolymerize isobutylene.

with the polar organic solvents are pentane, hexane, Exam 1e 2 octane,isopentane, isooctane, carbon disulfide, cyclopenp tane, cyclohexane,and methylcyclohexane. About 3 of Cobalt chloride was Plaeed in 10 Thisinvention has particular application in the producof methy1 Chloride atabout aud about tion of highly unsaturated gel-free copolymers ofisooletributyl um as add d to this slurry at 78 fins and multiolefins ofthe butyl rubber type. Incorpora- C- NO Change was obSeYVed- 5 ofisobutylene was tion of the multiolefin into the polymer is in thetrans-1,4- intfodueed- No Polymer was obtalued after about 24 position.hours at 78 C.

The expression butyl rubber as employed in the The Same experiment wasreproduced using as the specification and claims i intended to in l dcopolymers monomers 2.5 ml. of isobutylene and 2.5 ml. of butadiene;made from apolymerization reactant mixture having there- 25 again P ywas obtainedin about 7099.5% by weight of an isoolefin which hasEXPefimeut 2A was reproduced uslug 5 of ab ut 4-7 Carbon atoms and about-05% by weight of butadiene instead of the isobutylene. After 24 hoursat a conjugated multiolefin having about 4-14 carbon atoms. no P y wasobtained- The resulting copolymers contain about 85 to 99.5% of Example3 combined isoolefin and 0.5 to 15% of combined multiole- 3O fin. Theterm butyl rubber is described in an article by (A) About 1 t cobaltchltfnde w refluxed wlth R. M. Thomas et al. in Industrial Engineeringand Chemisabout 10 of alummum ethyl dlchtorlde at about 75 to try VOL32, 1283 et Seq October 1940 The PrePara- 80 C. for about one hour. Adark blue solution was obtion of butyl rubber is described in US. Pat.2,356,128, talned- The y t s l d at room temperature and which isincorporated herein by referehce 3 the excess undlssolved cobaltchloride filtered off. The

The process of this invention may he carried out using 0 alummum ethyldichloride-cobalt chloride complex was a monomer feed comprising about10 to about 90 volume found to contain about 0.67 g. of dissolved cobaltchlopercent isoolefin and about 90 to about 10 volume percent or about tptfrcent cobalt chlonde based on multiolefin. The copolymers of thisinvention may contain the alummum ethyl dtchlonde' as much as 90 wt.percent multiolefin. Preferably they 40 (B) A 2 volume t' j solution ofthe contain about 10 to about 80 wt. percent multiolefin, the Catalystof ExamPle 3A m meithyl ch10 dc was gradually remainder being isoolefin;more preferably, about 15 to added a Penod of ten minutes to gharge ofabout 50 wt percent of butadlene m 10 ml. of methyl chloride at 30 C.

The use of hydrocarbon solvents is detrimental to the After fi theRamon. w a f t process of this invention in that it results in lowermolecmethano T p0 yners i t were In ular weight products as compared toproducts prepared Y at In rare. ysls m mated t in the presence of polarsolvents. Additionally, the dommance oftranela:ueltsrlthsoee12-enchttmment catalysts of this invention will not copolymerize theisoole- Present There was no mdlcatlon of t' f l t fins and multiolefinsof this invention in the presence of (C) p was repeated at agammhydrocarbon solvents. The products so formed are sub- 50 frayedanalysls mdlcated h predommlmce of trans-L4- stantially mixtures ofhomopolymers of the individual isoumts and the .absence of i t' olefinsor multiolefins charged to the reaction vessel. The (D) Expenntent 3c wrepeated usmg lsoprene advantages of the catalyst system of thisinvention may stead of butttdlene' A yleld of about 152% of a 10w bemore readily appreciated by reference to the examples molecular WelghtProduct was obtamed' l W- Example 4 Examp 1e 1 To a charge of 200 ml. ofbutadiene and 400 ml. of

A Cobalt Complex of tributyl aluminum was P p methyl chloride at -30 C.was gradually introduced in the manner disclosed in Pat. 3,135,725-Example over a period of minutes, 6.6 ml. of an AlEtCl 'CoCl 1 of SaidPatent was reproduced using isobutylene instead catalyst complexsolution (2% in methyl chloride), said of butadlene 60 catalyst complexhaving been prepared in the manner of About 3 of anhydrous Cobaltehlonde were dlsllefsed Example 3A. After about 382 minutes, thereaction was In ml. of dry toluene and about ml. of trlbutyl terminatedquenching old methanol Aliquots alummum were added at room temperaturesome heat were withdrawn at 31, 72 and minutes. The results evolutionwas observed. The mixture was allowed to stand f these test are shown inTable I below.

TABLE I Percent Type of conver- Molecular Mole percent unsaturationMinutes of reaction sion weight I2 number unsaturation by IR Trans-1,4Trans-1,4 Trans-1,4

Trans-1,4

Hence, it is evident that since only trans-1,4 enchainment occurs in thepolymerization of butadiene with catalyst of the invention, the cobaltcomplex formed is not the same cobalt complex of the prior art suitablefor preparing cis-l,4- enchainment polymers.

Example Experiments were performed using the catalyst complex of Example1 and various isobutylene-butadiene monomer feeds. The results are shownin Table II.

TABLE IV Yield of Unsaturatlon Temperature, polymer, Molecular molecular5 C. grams weight I: number percent It is evident that the catalystcomplex of this invention 10 may be used to prepare low molecular, highunsaturates TABLE II Tem- S o1- per- Experiment Catalyst Charge Ventature Type of unsaturation A AlEtlClz con- 30 MeCl. -l00 Mainlytrans-1,4, some 1,2

tro

B A1EtClz.C0Cl2 30 Same 100 Do. 0... Same as above 65 do. 100 Do. D-..90 d0 -l00 Do. E. 70 do 100 Do. F. 70 o. 100 Do. G. 70 do 100 Do. H 70do 100 Do.

1 Charge comprises butadiene and isobutylene, the number shownindicating value percent butadiene.

These results indicate that the enchainment is substantially trans-1,4and hence, the catalyst complex is a cationic catalyst as distinguishedfrom prior art cobalt complexes which are coordination catalysts givingcis-1,4 enchainment.

Example 6 A monomer feed comprising 70 vol. percent butadiene and 30vol. percent isobutylene was polymerized using the catalyst system ofExample 1. The solvents used were or high molecular weight copolymerswith extraordinarily high levels of unsaturation, i.e. 12.75 molepercent.

Example 8 A monomer charge of 5 ml. of isobutylene in 15 ml. of methylchloride was polymerized using the cobalt complex of this invention. Thereaction was terminated after 12 minutes by quenching with methanol. Theexperiment was repeated using AlEtCl as the catalyst. The results areshown in Table V.

pentane and methyl chloride. The results are shown in Table III.

It is apparent that the catalyst complex of this invention results inmuch higher catalyst efliciency than conventional catalysts.

TABLE III Example 9 Charge I th f h hl d 1 n e preparatlon 0 1g yunsaturate copo ymers,

1 191 1 1 2. so vents mm gel formation often occurs. In order toevaluate the cata- 101' C4" Yield Weight lyst of this invention from thestandpoint of gel forma- H 1 C 10- Expedment ml ml 0 3C n 5 grams Xtion, a charge comprlsing 16 ml. of isobutylene and 184 A 135 315 2252,025 2 ml. of butadiene in 800 ml. of methyl chloride solvent waspolymerized at 100 C. The results are shown in Table VI.

TABLE VI Unsaturation, Gel Yield, Molecular mole content, grams weightIt number percent percent Catalyst:

AlEtCl2 32. 2 14, 620 141. 6 31. 15 17. 2 AlEtClz-CoClz. 16. 9 29, 230239. 8 52. 7e 4. 1

It is evident that the use of nonpolar solvents depresses the molecularweight of the copolymer formed.

Example 7 It is evident that the catalyst complex of this inventionproduces polymers having a higher molecular weight, higher mole percentunsaturation and a substantially lower gel content than conventionalcatalysts.

Example 10 Example 9 was repeated using a monomer charge comprising 70vol. percent butadiene and 30 vol. percent isobutylene in methylchloride. As shown in Table VII, the catalyst complex of this inventionproduces polymers of higher molecular weight and higher unsaturationthan conventional catalysts. Similar results were obtained usingisoprene as the conjugated multiolefin.

The monomer charge comprised 97 ml. isobutylene and 3 ml. of isoprene in400 ml. of methyl chloride. The reaction was carried out at 100 C.

TAB LE VII Charge Molecular Time, Yield, weight Catalyst, m1. iCr' ml.04" ml. CHaCl minutes grams I2 number Experiment number:

A AlEtCl2-CoClz. 135 315 2, 250 76 29. 5 318 46. 0 B Same as above 135315 2,250 130 37. 3 288 52.9 C AlEtCl: (control) 135 315 2, 250 103 11.0 179 36. 8

1 Infrared investigation showed predominantly trans-1,4 butadiene units,some 1,2 units and no cis-lA units.

Example 11 The results shown in Table VIII show that the CoCl Cobaltcomplexes of various cobalt salts were prepared complex producespolymers having higher unsaturation and used in the polymerization ofisobutylene-isoprene copolymer.

Catalyst preparation:

while CoBr and Co(acetonyl acetonate) result in polymers of substantialyhigher molecular weight and improved physical properties.

TABLE VIII Unsatun Molecular ation E10 nga- Yield, weight, mole Cure 1time, Modulus, Tensile, tion, grams 10- I2 number percent minutes 300%p.s.i. p.s.i. percent Catalyst:

714 3, 010 687 AlEtClz 31. 4 440 0. 72 1. 43 40 698 2, 764 660 60 499 2,87 6 707 20 742 2, 791 660 AlEtClz- C0012 30. 6 390 11. 6 1. 71 40 8022, 667 613 60 539 2, 608 720 20 473 3, 097 720 AlEtClg' C0131: 15. 8 6568. 8-1 1. 492 3, 139 740 60 317 2, 922 787 20 458 3, 383 767 AlEtClz-Co(acac)e 12. 5 918 7. 66 1. 13 40 533 3, 685 727 60 341 3, 325 800 1Cure recipe (in parts) polymer 15, stearic acid 0.15, PBN (phenyl-bctanaphthylamine) 0.15, ZnO 0.15, HAF black 7.5, Necton- 60 (a naphthenicat 307 F.

process oil) 1.5, Tuads (tetramethyl thiuram disulfide) 0.15, Altax(benzothiazyl disulfide) 0.15, sulfur 0.6. Cured Example 12 Example 11was repeated using a monomer charge comprising 80 ml. of isobutylene and20 ml. of butadiene in 400 ml. methyl chloride. As shown in Table IX,the catalyst complexes of this invention result in polymers havingsubstantially higher unsaturation than those pro in 10 ml. neat AlEtClwas heated to 80 C. for 2 hours duced with conventional catalysts.

TABLE IX Unsatur- Molecular ation Elonga- Yield, Weight, mole Cure 1time, Modulus, Tensile, tion, grams 10- I2 number percent minutes 00%p.s.i. p.s.i. percent Catalyst:

20 560 3, 043 740 AlEtClz 34 640 4. 3 0. 9 40 565 3, 040 740 480 3, 062753 20 897 3, 667 707 AlEtCly COCl2...-- 41 435 8. 21 1. 8 40 884 3, 037673 60 661 2, 559 673 20 810 2, 187 620 AlEtClz' OoBr 27. 6 253 11. 2 2.4 40 759 2, 040 613 60 602 1, 624 607 20 766 3, 022 693 AlEtClz'Co(acac) 2 25 340 8. 8 2. 0 40 660 2, 661 700 60 529 1, 811 673 1 Curerecipe same as in Example 11.

and filtered to remove the undissolved CoBr The filtrate was washed andweighed. The solution contained 0.434 g. (or 0.002 mole) CoBr i.e., theCo/Al ratio was 0.0208. This solution was diluted with methyl chlorideto give a 2 wt. percent solution.

(C) AlEtCl -Co(acetonyl acetonate) 1 g. of well dried Co(acac) wasplaced into 10 ml. neat AlEtCl and heated to 80 for 2 hours. Agreen-black solution was obtained. The undissolved residue was removedby filtration, washed with methyl chloride and weighed; 0.143 g. (or0.0033 mole) of Co(acac) dissolved which gives a Co/Al ratio of 0.034.This solution was diluted with methyl chloride to give a 2% solution.

Although preparation of the catalyst of this invention has beendescribed in terms of refluxing the constituents, it is obvious to thoseskilled in the art that alternately the reaction of the alkyl aluminumdihalide and cobalt salt may be carried out under pressure withoutrefluxing. The only requirements necessary in carrying out thisinvention are that the catalyst be prepared by reacting the alkylaluminum dihalide and cobalt salt (1) in the absence of hydrocarbonsolvent, (2) at a temperature above 50 C., but below the decompositiontemperature of the reactants. The polar solvents of this invention maybe used in preparation of the catalyst. It is preferred, however, thatthe catalyst be prepared in the absence of solvent.

The pressure at which the reaction is carried out is not critical solong as the temperature requirements are met. Superatmospheric pressuresmay be used. Where it is desired not to reflux, the pressures must besuch that the alkyl aluminum dihalide remains substantially in theliquid form. Illustrative of suitable pressures are about 1 atm. to10,000 atm.; preferably about 1 atm. to about 1,000 atm.; morepreferably about 1 atm. to 500 atm.; most preferably about 1 to about 50atm.

Though the upper temperature limitation is the decomposition temperatureof the alkyl aluminum dihalide, it is preferred that the reaction becarried out at about 50 C. to about 350 C.; more preferably about 60 C.to about 250 C.; most preferably about 70 C. to about 200 C. Whererefluxing is used the ideal temperature range is about 50 C. to about100 C. The minimum temperature of about 50 C. applies whether or notrefluxing is used. Preferably, the minimum reaction temperature is about60 C.; more preferably about 70 C. The reaction is carried out over aperiod of 30 minutes to about 24 hours; preferably about 45 minutes toabout 18 hours; more preferably about 1 to about 3 hours.

What is claimed is:

1. A process for preparing a catalyst useful in the copolymerization ofisoolefins and multiolefins which comprises:

(a) refluxing a cobalt salt selected from the group consisting of cobaltchloride, cobalt bromide, cobalt acetonyl acetonate, cobalt acetate andmixtures thereof with an alkyl aluminum dihalide having the generalformula:

' AlRXg wherein R is a hydrocarbon radical selected from the groupconsisting of C to C alkyl, phenyl, C to C aralkyl and C to C alkylaryl;at a temperature of about 50 to about 100 C. and X is halogen;

(b) cooling the mixture; and

(c) separating the liquid portion of the reaction from the unreactedcobalt salt.

2. The process of claim 1 wherein the alkyl aluminum dihalide isaluminum ethyl dichloride and the cobalt salt is CoCl 3. The product ofclaim 1.

4. A process for preparing a copolymer of an isoolefin and a conjugatedmultiolefin which comprises:

(a) preparing a catalyst complex by (l) refluxing a cobalt salt selectedfrom the group consisting of cobalt chloride, cobalt bromide, cobaltacetonyl acetonate, cobalt acetate and mixtures thereof with an alkylaluminum dihalide having the general formula:

wherein R is a hydrocarbon radical selected from the group consisting ofC to C alkyl, phenyl, C to C aralkyl, and C7 to C alkylaryl and X ishalogen; at a temperature of about 50 to about 100 C.;

(2) cooling the mixture, and

(3) separating the liquid portion of the reaction from the unreactedcobalt salt;

(b) dissolving said catalyst complex in a polar organic solvent; and

(c) adding a catalytic amount of said catalyst solution to a solution ofat least one isoolefin and at least one conjugated multiolefin in apolar organic solvent at a temperature of about --20 C. to about 120 C.

5. The process of claim 4 wherein the isoolefin is isobutylene and themultiolefin is isoprene.

6. The process of claim 4 wherein the monomer feed comprises about toabout 90 volume percent of multiolefin.

7. In a process for preparing butyl rubber, the improvement whichcomprises using as the catalyst a cobalt complex prepared by:

(a) refluxing a cobalt salt selected from the group consisting of cobaltchloride, cobalt bromide cobalt acetonyl acetonate, cobalt acetate andmixtures thereof with an alkyl aluminum dihalide having the generalformula:

AlRX

wherein R is a hydrocarbon radical selected from the group consisting ofC to C alkyl, phenyl, C to C aralkyl and C to C alkylaryl and X ishalogen; at a temperature of about 50 to about C. for at least one hour;(b) cooling the mixture; (c) separating the liquid portion of thereaction from the unreacted cobalt salt; and (d) dissolving the complexso formed in an organic polar solvent. 8. The process of claim 7 whereinthe isoolefin is isobutylene and the multiolefin is isoprene.

9. A process for preparing a polymer of a conjugated multiolefin whichcomprises:

(a) preparing a catalyst complex by (1) refluxing a cobalt salt selectedfrom the group consisting of cobalt chloride, cobalt bromide, cobaltacetonyl acetonate, cobalt acetate and mixtures thereof with an alkylaluminum dihalide having the general formula:

AlRX wherein R is a hydrocarbon radical selected from the groupconsisting of C to C alkyl, phenyl, C to C aralkyl, and C to C alkylaryland X is halogen; at a temperature of about 50 to about l00 C.;

(2) cooling the mixture, and (3) separating the liquid portion of thereaction from the unreacted cobalt salt;

(b) dissolving said catalyst complex in a polar organic solvent; and

(0) adding a catalytic amount of said catalyst solution to a solution ofat least one conjugated multiolefin in a polar organic solvent at atemperature of about -20 C. to about C.

10. The process of claim 9 wherein the multiolefin is butadiene,chloroprene, isoprene, or mixtures thereof.

11. The process of claim 4 wherein the solvent comprises a polar organicsolvent and a minor amount of a nonpolar hydrocarbon solvent.

12. The process of claim 9 wherein the solvent comprises a polar organicsolvent and a minor amount of a nonpolar hydrocarbon solvent.

13. A process for preparing a catalyst useful in the copolymerization ofisoolefins and multiolefins which comprises:

(a) reacting a cobalt salt selected from the group consisting of cobaltchloride, cobalt bromide, cobalt acetonyl acetonate, cobalt acetate andmixtures thereof with an alkyl aluminum dihalide having the generalformula: AlRX wherein R is a hydrocarbon radical selected from the groupconsisting of C to C alkyl, phenyl, C to C aralkyl and C to C alkylaryland X is halogen; at a temperature of at least 50 C.;

(b) cooling the mixture; and

(c) separating the liquid portion of the reaction from the unreactedcobalt salt.

14. The process of claim 13 wherein the alkyl aluminum dihalide isaluminum ethyl dichloride and the cobalt salt is CoCl 15. A process forpreparing a copolymer of an isoolefin and a conjugated multiolefin whichcomprises reacting at least one isoolefin and at least one conjugatedmultiolefin in a polar solvent at a temperature of about 20 C. to about120 C. in the presence of a catalytic amount of the catalyst of claim 3.

12- 16. The process of claim 15 wherein the isoolefin is ReferencesCited isobutylene and the multiolefin is isoprene. i UNITED STATESPATENTS 17. In a process for preparing butyl rubber, the improvementwhich comprises using as the catalyst the 3,135,725 6/1964 Carlson et26ow94-3 catalyst of claim 3.

18. The process of claim 17 wherein the isoolefin is 5 JOSEPH SCHOFERPrimary Examiner isobutylene and the multiolefin is isoprene. R. A.GAITHER, Assistant Examiner 19. A process for preparing a polymer of aconjugated multiolefin which comprises polymerizing said multiolefinU.S. Cl. X.R.

usin as the o1 merization initiator the catal st of chili 3 p y Y 10252-429, 431, 260-943, 87.5

